Dan or Justy

Oztek: Sunday

Today the theme was decompression. We took in a very accessible talk by Dr. Andrew Fock on a comparison of the Haldane and Bubble Models. Lots of pretty pictures and helpful info.

There was a panel discussion later on "Why are so many techincal divers getting bent?" The consensus revolved around 3 points:

1. More extreme dives are being attempted.
2. More aggressive schedules are being followed.
3. There is a general lack of appreciation for individual variation vs. strong focus on model choice. The former is much bigger than the latter. This is a hugely important point.

Dr. Mitchell also led an accident analysis for the recent death of David Shaw in South Africa. Shaw was attempting to retrieve the body of a diver lost 10 years earlier in the Boesmangat cave, at a depth of roughly 900 feet. There is no safe way to do this. On his first dive in the cave, he aborted his mission to set a depth record when he found the body. Before he left, he laid some line to help find the body quickly on a subsequent dive.

Shaw took a month to plan a return. He wore a head-mounted video camera, which is why we know so much about his demise. Mitchell was at pains to point out that he wasn't criticizing Shaw, and that this kind of accident analysis is intended to help the living stay that way. Shaw already paid the ultimate price for his mistakes. We shouldn't pile on.

Mitchell did not show the video. He talked us through what it shows. The line laid on the previous dive was quite slack and laying about on the cave floor. The work of dealing with the body was greater than Shaw anticipated (the body was half-skeletal and half intact, but buried in mud). The combination of increased taskload, at least a 150' equivalent narcotic depth, and the work of breathing gas at 28 atmospheres all added up to CO2 buildup. He died gasping for breath, entangled in his own line, an unused pair of scissors in his hand.

Mitchell then showed pictures of the teardown of Shaw's rebreather. There were non-stock parts at several points that obviously increased the work of breathing. What's amazing is that Shaw was able to function, just, in spite of these maladaptations. When he ventured near the limits of human survivability, he failed.

We ended the day at the IMAX theater taking in James Cameron's latest submersible adventure. Cameron's co-producer, Andrew Wight, was in attendance and gave a highly photographic talk about the logistical challenges of multi-ocean, multi-submersible, sea-floor diving. "Aliens of the Abyss" is a fun trip.

I can't comment on the photo track talks, but of them Leigh Bishop from the UK stands out. He and his group specialize in sunk ocean liners. There are very many near the UK, but most are in hard to reach places. And deep, to boot. He specializes in the tripod-enabled long exposure shots. His results are stellar.

It was something he said, however, that has stayed with me. He said we are living in the golden era of shipwreck discovery. Not all that long from now, these wrecks will be iron deposits on the ocean floor. A sobering thought and one that gets me excited about what is possible.